1. Field of the Invention
This invention relates generally to building materials and more specifically to building materials in which a desired final composition and ratio of Struvite-K and Syngenite, two minerals not normally found together, is provided to impart specified and predetermined properties and characteristics to the building materials.
2. Background Art
For approximately three thousand years, and at least since Roman times, magnesium oxide (MgO) based cements have been used to build walls and structures. Within the last 50 years, improved magnesium oxide containing materials have been used for batch manufacture of slurries that are then poured into panel molds where they are allowed to cure for an extended period of time. The resulting products impart rigidity and structural integrity to the panel and thereby allow the panel to be fastened to wall assemblies.
Wallboard typically has a density range of from about 1,600 pounds (lbs.) to about 1,800 lbs. per thousand square feet (lbs/MSF) (about 7.8 kilograms (kg) to about 8.3 kg per square meters (m2)) of about one-half inch (1.27 cm) board. Heavy or high-density gypsum wallboards are costly and more difficult to manufacture, transport, store, and manually install at job sites. The recent trend has been toward lighter or low-density boards. While wallboards having reduced densities through adding lightweight fillers and foams are known, wallboard having a density of less than about 1,600 lbs/MSF (about 7.8 kg per m2) in a one-half inch (1.27 cm) board, may reduce the strength and integrity of the resulting board. Because extra high-density or heavy gypsum wallboard generally is not desirable for the reasons set forth above, research and development are proceeding apace in order to produce reduced weight or density boards without sacrificing board integrity and strength. One method of reduction of board weight is to use novel or non-gypsum materials for the core of the boards.
Struvite [(NaH4(PO4).6(H2O)] has been known as a naturally occurring mineral for over a century, and has been the subject of study in the health process of animals and sewage treatment. See, for example, US Published Patent Appl. No. 2013/0062289, among others. A more recent development has resulted in a similar, albeit artificially created, mineral, alternatively known as K-Struvite, Struvite-K or Struvite (K) (hereinafter “Struvite-K”), having the chemical formula [KMg(PO4).6(H2O)]. This essentially man-made mineral has been the subject of intense study because many of its salient characteristics, including its orthorhombic crystal structure, glassy sheen, which permits substantially friction free motion, and resistance to heat transfer, have been found very suitable in the building industry.
Because of these and other properties, and from the desire in the building and construction industries to find a feasible alternative to gypsum boards as internal building materials, Struvite-K has been determined to provide a good heat resistant building board panel while remaining slightly elastic and providing ease of manufacture on a mass scale comparable to that of gypsum board.
It is well known that such magnesium oxychloride containing panels are more expensive, usually amounting to twice to three times the cost of traditional gypsum building panel alternatives, see for example, US Pat Pub. Nos. 2013/0115838 published on May 9, 2013. Therefore, these types of boards are not widely accepted as cost affordable building materials for wall boards or panels. Moreover, some magnesium oxychloride containing building panels produce free chlorine gas within the board material, and thus present major issues, such as leaching, foul odors, fastener and building structure corrosion. In addition, many of these types of boards will breakdown and decompose over time, as they are not chemically stable. These types of boards and panels are particularly susceptible to long term water exposure, and are prone to fall apart under long exposures to such conditions.
In recent years, environmental and health safety driven building codes have mandated that only building materials capable of offering improved water resistance and or fire resistance can be used in certain construction structures and building methods. As a result, paperless gypsum and traditional cement building panels have evolved to satisfy these requirements. However, gypsum is not and cannot ever be water proof and or completely water resistant. Therefore, it is necessary that water resistant compounds, such as waxes or silicones, be added to their formulation to impart acceptable water resistance. This may be a costly and perhaps unnecessary addition.
Moreover, the traditional fiber cement and Portland cement building panels are extremely difficult to handle and work with when used in traditional building practices, and thus require more time, labor and specialized tools to prepare and install these types of building panels.
More recently, the international economic situation has affected the building and construction markets. Consequently, construction companies have been driven to seeking alternative building materials that offer improved performance characteristics that are at least an order of magnitude greater than those of traditional gypsum and cement building materials, while simultaneously matching the cost effectiveness of gypsum and cement building materials.
This invention addresses the simultaneous tension between cost and effectiveness, while providing for a method of using a continuous board line. The dual considerations of functional effectiveness and reduction of costs, in the context of improved and engineered building materials designed to serve specific purposes, would provide an ideal building material if all the considerations are adjusted to obtain such boards or panels. None of the heretofore disclosed known prior art building board compositions can provide these capabilities. None of the prior art methods known heretofore teach the inventive process of forming composite boards containing synthetic Struvite-K and Syngenite in specified ratios so as to provide desired characteristics and features on wall board panels, utilizable to provide an ultra-lightweight board or building panel, that is moisture and fire resistant.